The present application claims priority under 35 U.S.C. xc2xa7119 to Japanese Patent Application No. 2001-323732, filed on Oct. 22, 2001, entitled xe2x80x9cMETHOD AND APPARATUS FOR MEASURING GAP, METHOD AND APPARATUS FOR MEASURING SHAPE AND METHOD FOR MANUFACTURING LIQUID CRYSTAL DEVICExe2x80x9d. The contents of that application are incorporated herein by reference in their entirely.
1. Technical Field to Which the Invention Belongs
The present invention relates to technology for measuring a clearance (gap) between members or a shape thereof by utilizing interference of light.
2. Description of the Related Art
Conventionally, as an apparatus for measuring a gap in a light transmission member such as a liquid crystal cell, for example, there has been employed such a gap measuring apparatus as shown in a configuration diagram in FIG. 19. This gap measuring apparatus utilizes a phenomenon that refractive waves from a top face and a bottom face of a gap in actual thickness xe2x80x9cdxe2x80x9d (refraction index of a medium is defined as xe2x80x9cnxe2x80x9d) illuminated by an objective lens of a microscope via a half mirror return with a second phase difference, and these two lights pass through a Wollaston prism and polarizing plates A and P, thereby producing an interference fringe. That is, a peak gap xe2x80x9cyxe2x80x9d between an interference fringe caused by the refractive lights of the top face and bottom face and an interference fringe in cross line on the refractive wave face between the top face and bottom face is measured, whereby a value of the gap xe2x80x9cdxe2x80x9d is obtained by the following formula (1):
y=nd/(nexe2x88x92no)tan xcex8xe2x80x83xe2x80x83(1) 
where xcex8 denotes a Wollaston prism angle, and ne and no each denote a refractive index of the Wollaston prism angle.
However, the above described conventional gap measuring instrument is intended for measuring one point of an object. In order to measure a gap distribution in a predetermined section, measurement must be repeated while such an object is being moved, which is complicated in work and requires much time.
The present invention in accomplished taking the foregoing problem into consideration. Accordingly, an object of the invention is to provide a method and apparatus capable of measuring a gap between objects or a shape of such an object with a high speed and high precision and a method for effectively manufacturing a liquid crystal device.
To achieve the foregoing object, the present invention adopts the following structures.
(1) A gap measuring method characterized by comprising the steps of:
applying a plurality of color lights to a member provided with a gap, to produce color interference fringes;
obtaining respective intensities of the color lights in the images of the interference fringes taken by a color camera, at each of predetermined positions of each image, so as to compute an actual ratio among (or of) the obtained intensities of the color lights for each of the predetermined positions; and
obtaining gap values of a plurality of points of the gap provided in the member, based on said actual ratio and theoretical ratios each of which is computed based on intensities of said color lights in an image, correspondingly to each of preliminarily set gap values.
(2) A gap measuring method in (1), characterized in that the interference fringe is obtained by using transmitted light through the member.
(3) A gap measuring method in (1), characterized in that the interference fringe is obtained by using reflected light from the member.
(4) A gap measuring method in any one of (2)xcx9c(3), characterized in that a composite light including said plurality of color lights is applied to the member.
(5) A gap measuring method in any one of (2)xcx9c(3), characterized in that white light including said plurality of color lights is applied to the member, and that a filter is provided for transmitting the plurality of color light to the color camera.
(6) A gap measuring method in any one of (1)xcx9c(5), characterized in that the intensities of the each color light in the images taken up by the color camera are corrected in consideration of a variable element for the each color light.
(7) A gap measuring method in any one of (1)xcx9c(6), characterized in that each of the images is composed of a plurality of pixels, and gap measurement is carried out for each pixel.
(8) A shape measuring method utilizing the gap measuring method in (1)xcx9c(7), characterized in that one of members defining a gap is made into a plate-shaped element with a flat surface to effect the measurement, and the shape of the other member defining the gap is determined on the basis of the thus obtained gap measurement value.
(9) A gap measuring apparatus characterized by comprising:
a light source for applying a plurality of different color lights to an object to be measured having light transmission properties;
a color camera for picking up images of interference fringes formed by the light transmitted through the object to be measured;
an image memory for storing images picked up by the color camera;
computing means for obtaining respective intensities of the color lights in the images at each of predetermined positions of each image, so as to compute an actual ratio among (or of) the obtained intensities of the color lights for each of the predetermined positions;
a reference data memory for storing theoretical ratios among (or of) intensities of said color lights in an image, correspondingly to each of preliminarily set gap values; and
gap value comparing/determining means for determining gap values of a plurality of points of a gap provided in the object to be measured according to the actual ratio and the theoretical ratios.
(10) A gap measuring apparatus characterized by comprising:
a light source for applying light to an object to be measured having light transmission properties;
a color camera for picking up images of interference fringes formed by the light transmitted through the object to be measured;
a filter for transmitting a plurality of different color lights to the color camera;
an image memory for storing images picked up by the color camera;
computing means for obtaining respective intensities of the color lights in the images at each of predetermined positions of each image to compute an actual ratio among (or of) the obtained intensities of the color lights for each of the predetermined positions;
a reference data memory for storing theoretical ratios among (or of) intensities of said color lights in an image correspondingly to each of preliminarily set gap values; and
gap value comparing/determining means for determining gap values of a plurality of points of a gap provided in the object to be measured according to the actual ratio and the theoretical ratios.
(11) A gap measuring apparatus characterized by comprising:
a light source for emitting a plurality of different color lights;
a color camera for picking up images of light interference fringes;
optical means for directing the lights from the light source toward an object to be measured and directing reflected lights thereof from the object to be measured toward the color camera;
an image memory for storing images of the interference fringe formed by the lights from the optical means and picked up by the color camera;
computing means for obtaining respective intensities of the color lights in the images at each of predetermined positions of each image, so as to compute an actual ratio among (or of) the obtained intensities of the color lights for each of the predetermined positions;
a reference data memory for storing theoretical ratios among (or of) intensities of said color lights in an image, correspondingly to each of preliminarily set gap values; and
gap value comparing/determining means for determining gap values of a plurality of points of a gap provided in the object to be measured according to the actual ratio and the theoretical ratios.
(12) A gap measuring apparatus characterized by comprising:
a light source for emitting light;
a color camera for picking up images of light interference fringes;
a filter for transmitting a plurality of different color lights to the color camera;
optical means for directing the light from the light source toward an object to be measured and directing reflected light thereof from the object to be measured toward the color camera;
an image memory for storing images of the interference fringe formed by the light from the optical means and picked up by the color camera;
computing means for obtaining respective intensities of the color lights in the image at each of predetermined positions of each image, so as to compute an actual ratio among (or of) the obtained intensities of the color lights for each of the predetermined positions;
a reference data memory for storing theoretical ratios among (or of) intensities of said color lights in an image correspondingly to each of preliminarily set gap values; and
gap value comparing/determining means for determining gap values of a plurality of points of gap provided in the object to be measured according to the actual ratio and the theoretical ratios.
(13) A gap measuring apparatus in any one of (9)xcx9c(12), characterized by further comprising correction means for correcting the intensities of the each color light of the images picked up by the color camera in consideration of a variable element for the each color light.
(14) A shape measuring apparatus characterized by comprising:
a light source for applying a plurality of different color lights to a measurement object having light transmission properties;
a light transmission plate shaped element with a flat surface disposed apart by a gap the object to be measured;
a color camera for picking up images of interference fringes formed by the lights transmitted through the object to be measured and the light transmission plate shaped element;
an image memory or storing images picked up by the color camera;
computing means for obtaining respective intensities of the color lights in the images at each of predetermined positions of each image, so as to compute an actual ratio among (or of) the obtained intensities of the color lights for each of the predetermined positions;
a reference data memory for storing theoretical ratios among (or of) intensities of said color lights in an image correspondingly to each of preliminarily set gap values;
gap value comparing/determining means for determining gap values of a plurality of points of a gap provided in the object to be measured according to the actual ratio and the theoretical ratios; and
gap value/shape converting means for determining a shape of the object to be measured on the basis of the gap values obtained by the gap value comparing/determining means.
(15) A shape measuring apparatus characterized by comprising:
a light source for applying light to an object to be measured having light transmission properties;
a light transmission plate-shaped element with a flat surface disposed apart by a gap from the object to be measured;
a color camera for picking up images of interference fringes formed by the lights transmitted through the measurement object and the light transmission plate shaped element;
a filter for transmitting a plurality of different color lights to the color camera;
an image memory for storing images picked up by the color camera;
computing means for obtaining respective intensities of the color lights in the images at each of predetermined positions of each images so as to compute an actual ratio among (or of) the obtained intensities of the each color lights for each of the predetermined positions;
a reference data memory for storing theoretical ratios among (or of) intensities of said color lights in an image correspondingly to each of preliminarily set gap values;
gap value comparing/determining means for determining gap values of a plurality of points of a gap provided in the object to be measured according to the actual ratio and the theoretical ratios; and
gap value/shape converting means for determining a shape of the object to be measured on the basis of the gap values obtained by the gap value comparing/determining means.
(16) A shape measuring apparatus characterized by comprising:
a light source for emitting a plurality of different color lights;
a light transmission plate shaped element with a flat surface disposed apart by a gap from an object to be measured;
a color camera for picking up images of light interference fringes;
optical means for directing the light from the light source toward the object to be measured and the light transmission plate shaped element and directing reflected lights thereof from the object to be measured and the light transmission plate shaped element toward the color camera;
an image memory for storing images of the interference fringe formed by the lights from the optical means and picked up by the color camera;
computing means for obtaining respective intensities of the color lights in the images at each of predetermined positions of each image, so as to compute an actual ratio among (or of) the obtained intensities of the each color lights for each of the predetermined positions;
a reference data memory for storing theoretical ratios among (or of) the intensities of said color lights in an image correspondingly to each of preliminarily set gap values;
gap value comparing/determining means for determining gap values of a plurality of points of a gap provided in the object to be measured according to the actual ratio and the theoretical ratios; and
gap value/shape converting means for determining a shape of the object to be measured on the basis of the gap values obtained by the gap value comparing/determining means.
(17) A shape measuring apparatus characterized by comprising:
a light source for emitting light;
a light transmission plate-shaped element with a flat surface disposed apart by a gap from an object to be measured;
a color camera for picking up images interference fringes of light;
a filter for transmitting a plurality of different color lights to the color camera;
optical means for directing the light from the light source toward the object to be measured and the light transmission plate-shaped element and directing reflected lights thereof from the object to be measured and the light transmission plate-shaped element toward the color camera;
an image memory for storing images of the interference fringes formed by the lights from the optical means and picked up by the color camera;
computing means for obtaining respective intensities of the color lights in the images at each of predetermined positions of each image, so as to compute an actual ratio among (or of) the obtained intensities of the color light;
a reference data memory for storing theoretical ratios among (or of) the intensities of said color lights in an image correspondingly to each of preliminarily set gap values;
gap value comparing/determining means for determining gap values of a plurality of points of a gap provided in the object to be measured according to the actual ratio and the theoretical ratios; and
gap value/shape converting means for determining a shape of the object to be measured on the basis of the gap values obtained by the gap value comparing/determining means.
(18) A shape measuring apparatus characterized by comprising:
a light source for emitting a composite light of a plurality of different color lights;
a color camera for picking up images of light interference fringes;
a reference reflective member for reflecting light;
optical means for directing the light from the light source as an object light toward an object to be measured so as to direct reflected light thereof from the object to be measured toward the color camera, and for directing the light from the light source as a reference light toward the reference reflective member so as to direct reflected light thereof from the reference reflective member toward the color camera;
an image memory for storing images of the interference fringes formed by the lights from the optical means and picked up by the color camera;
computing means for obtaining respective intensities of the color lights of the images at each of predetermined positions of each image, so as to compute an actual ratio among (or of) the obtained intensities of the color light;
a reference data memory for storing theoretical ratios among (or of) the intensities of said color lights in an image correspondingly to each of preset optical path differences;
optical path difference comparing/determining means for determining differences at a plurality of points between an optical path between the optical means and the object to be measured and an optical path between the optical means and the reference reflective member according to the actual ratio and the theoretical ratios; and
an optical path difference/shape converting means for determining a shape of the object to be measured on the basis of the optical path differences obtained by the optical path difference comparing/determining means.
(19) A shape measuring apparatus characterized by comprising:
a light source for emitting light;
a color camera for picking up images of light interference fringes;
a filter for transmitting a plurality of different color lights to the color camera;
a reference reflective member for reflecting light;
optical means for directing the light from the light source as an object light toward an object to be measured so as to direct and directing the light from the light source as a reference light so as to direct reflected light thereof from the reference reflective member toward the color camera;
an image memory for storing images of the interference fringe formed by the lights from the optical means and picked up by the color camera;
computing means for obtaining respective intensities of the color lights of the images at each of predetermined positions of each image, so as to compute an actual ratio among (or of) the obtained intensity of the color lights;
a reference data memory for storing theoretical ratios among (or of) the intensities of said color lights in an image correspondingly to each of preset optical path differences;
optical path difference comparing/determining means for determining differences at a plurality of points between an optical path between the optical means and the object to be measured and an optical path between the optical means and the reference reflective member according to the actually measured ratio and the theoretical ratio; and
an optical path difference/shape converting means for determining a shape of the object to be measured on the basis of the optical path differences obtained by the optical path difference comparing/determining means.
(20) A shape measuring apparatus in any one of (14)xcx9c(19), characterized by further comprising correction means for correcting the intensities of the color lights of the images picked up by the color camera in consideration of a variable element for the each color light.
(21) A method for manufacturing a liquid crystal device in which liquid crystal is injected and sealed in a gap between two substrates, wherein, utilizing the gap measuring apparatus according to any one of (9)xcx9c(13), a gap value of the gap is measured, so that liquid crystal is injected into the gap when the gap value is in a predetermined range.